CDK4 and Familial prostate cancer: In tongue squamous cell carcinoma, analogous results were observed, and CBX3 overexpression inhibited p21 expression and promoted the G1/S phase transition in the cell cycle.[26] Furthermore, CBX3 was reported to inhibit p21 in a CDK6‐independent manner to promote cell cycle progression in colon cancer.[38] We examined the effect of palbociclib on tumor cells and showed that after CBX3 knockdown or overexpression in Rb1‐deficient prostate cancer cells, RB1 was found to be a crucial component in CBX3‐mediated regulation of PC cell sensitivity to CDK4/6 inhibitors.